A lot of the time when I use the undo keyboard shortcut absolutely nothing happens. Occasionally it does work.
It's pretty terrible when I'm painting as I routinely take a lot of strokes before I settle on one I like.. Having to go over and click in the history palette makes Photoshop CC almost unusable for me.
I'm running it on OS X 10.9 Mavericks (latest dev preview) - so it might just be that. Anyone have a fix for this?
No solution, just a "Me Too" My Cintiq undo button works, sometimes, but not the keyboard version.
Perhaps check in Photoshop CC's Keyboard Shortcuts to see if there's a conflict?
Sorry can't be of help- busy working out why all my CS3 brushes have their Texture Depth set wrong on Import
Another me, too.
I recently updated Photoshop CC to 2014.2.1 on my Macbook Pro running OS X 10.9.5, and I'm having the same problem. I can use Edit>Step Backward, but not Undo. Just gets me a loud beep. This is a new behavior and a real problem for me. I haven't changed any keyboard shortcuts in Photoshop, so that's probably not my problem.
Sorry I couldn't help, either.